US2226728A - Transmission device - Google Patents

Transmission device Download PDF

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Publication number
US2226728A
US2226728A US265476A US26547639A US2226728A US 2226728 A US2226728 A US 2226728A US 265476 A US265476 A US 265476A US 26547639 A US26547639 A US 26547639A US 2226728 A US2226728 A US 2226728A
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United States
Prior art keywords
band
frequency
frequencies
path
filter
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Expired - Lifetime
Application number
US265476A
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English (en)
Inventor
Lalande Marc Andre
Gloess Paul Francois Marie
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International Standard Electric Corp
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International Standard Electric Corp
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Filing date
Publication date
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Publication of US2226728A publication Critical patent/US2226728A/en
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    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04N—PICTORIAL COMMUNICATION, e.g. TELEVISION
    • H04N5/00—Details of television systems
    • H04N5/14—Picture signal circuitry for video frequency region
    • H04N5/16—Circuitry for reinsertion of DC and slowly varying components of signal; Circuitry for preservation of black or white level
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04B—TRANSMISSION
    • H04B3/00—Line transmission systems
    • H04B3/02—Details
    • H04B3/04—Control of transmission; Equalising
    • H04B3/10—Control of transmission; Equalising by pilot signal
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04N—PICTORIAL COMMUNICATION, e.g. TELEVISION
    • H04N7/00—Television systems
    • H04N7/10—Adaptations for transmission by electrical cable

Definitions

  • the present invention relates to electric signaltransmission systems, particularly to systems intended for transmitting a very wide frequency band.
  • the invention more specifically relates to systems in which the frequency band to be transmitted is divided into two bands A and B.
  • the band A contains the lower frequencies which are normally badly transmitted by the transmission apparatus and the band B contains the higher frequencies. modification.
  • the band A is modulated at a particular carrier frequency of such value that the band A is transmitted consequently as a frequency band higher than the band of frequencies B which itself is transmitted without modification.
  • the products of modulation of the band A are separated from the band B and demodulated.
  • the original frequency band A is thus obtained and is then re-mixed with the band B which is transmitted directly and without modification, the original frequency band 30 A+B, thereby being reconstructed.
  • An electric signal transmission system of the kind referred to, according to the present invention is characterised in this, that the higher band of frequencies is obtained by balancing out the lower band of frequencies by current of the same magnitude but of opposite phase in a first path, the lower band of frequencies being transmitted in a second path to a modulator of higher frequency than the signal of highest frequency, the output of both paths being applied together to the transmission channel.
  • Fig. 1 represents the frequency range to be transmitted
  • Fig. 2 represents the division'of the frequency band to be transmitted into two bands A and B.
  • the band B is transmitted without Fig. 3 shows the band B directly transmitted and the products of the modulation of the lower band A;
  • Figs. 4, 5 and 6 show the division into two bands in accordance with the invention
  • Fig. 7 shows a basic diagram of the embodiment of the invention for the division of the two bands transmitted
  • Fig. 8 is a diagram employed in the description
  • Fig. 9 shows an artificial line employed in the system
  • Figs. 10, 11, 12, 13 and 14 are diagrams employed in order to explain the operation of the artificial line of Fig. 9;
  • Fig. 15 a particular embodiment of this artificial line
  • Fig. 16 shows curves relating tothe above artificial lines
  • Fig. 17 shows an embodiment of the invention for reception.
  • Certain devices employed transmit easily only frequencies higher, for example, than kilocycles, and the theoretical division of the original frequency band of three megacycles of Fig. 1 is provided at kilocyclesas shown in Fig. 2 for reasons which will appear later on.
  • the band A comprising the frequencies from 0 to 120 kilocycles is modulated after separation at a carrier frequency of 3.5 megacycles so that no modulation product falls in the band B from 120 kilocycles to 3 megacycles which is transmitted without modification.
  • the two sidebands of modulation obtained by modulating the band A with 3.5 megacycles are represented by A1 and A2 in Fig. 3.
  • a low pass filter is provided in connection with the circuit shown schematically in Fig. 7.
  • the signals constituting 10 the complete band to be transmitted arrive at V.
  • the current is then divided into two paths, one transmitting the band A and the other the band B.
  • the path serving for the transmission of the lower band A contains a low-pass filter I which 15 practically introduces neither phase distortion nor attenuation up to a frequency of 60 kilocycles.
  • Such filters which practically introduce no appreciable phase distortion or attenuation dis- 20 tortion up to 0.5 of the cut-off frequency are wellknown in the art.
  • the output of the filter I is applied simultaneously to a modulator 2 and to a valve 3 the plate circuit of which is connected in parallel to the plate circuit of a valve 4 connected in the other path of the circuit and transmitting the higher frequency band B.
  • valve 5 constituting a phase inverting circuit
  • the currents arriving at the valve 4 are in phase opposition with those which have passed through the filter I ,and arrive at the valve 3.
  • the gain of the valves 3, 4 and 5 it is thus possible to obtain that for all the frequencies which pass through the low-pass filter I without phase distortion or attenuation distortion, the currents 45 in the common plate circuit of valves 3 and 4 are -of equal amplitude and of opposite phase, and cancel each other.
  • the vector OV represents the incoming signal V.
  • the portion of the current passing through the valve 5, the retardation line 6 and the valve 4 65 arrives on the line circuit connected to the plate circuit of this valve 4, and may be represented by the vector OB.
  • That portion of the current passing through the low-pass filter I is attenuated and retarded
  • a portion represented by the vector 0A passes directly through the modulator 2.
  • this vector 0A gives a resulting vector 00 which is transmitted, and the amplitude of which depends upon the transmission through the filter I.
  • the vector OA decreases in proportion as the attenuation of the low-pass filter I increases from 60 to 200 kilocycles. On the other hand for frequencies lower than 60 kilocycles, for
  • the retardation line 6 (Fig. 7) should introduce practically without attenuation a delay in transmission equal to that introduced by the lowpass filter I. It is possible to employ for this purpose a retardation line of the type shown in Fig. 9. Such lines can also be employed with advantage when it is desired to obtain a constant retardation, that is to say, a variation of phase of the current transmitted in proportion to the frequency.
  • the retardation lines employed hitherto comprise inductances in series and condensers in shunt, and constitute a low-pass filter shown in Fig. 11' of the cut-off frequency:
  • This method already permits the amount of space taken up to be reduced by reducing the number of elements.
  • Fig. 9 shows an artificial line in which a coupling is established between all the adjacent se- 6 ries inductances contrary to the arrangements hitherto used.
  • the impedance and the cut-off frequency are determined by the value of the condensers employed, the diameter of the wire employed, the
  • the termination of such a line may be effected only in mid-series. In this case the coupling between the last section and the final half-section must be equal to 2 times the coupling between consecutive elements, and is thus 0.168 in the example described. It is then necessary to employ a different diameter of wire for the final half-section. It is also possible to terminate the line in mid-series followed by a half-section of a proto-type filter. In
  • This method has the drawback of introducing a section having a slight distortion of the transmission time. It is, moreover, possible to compensate the slight distortion thus produced by utilising sections having values of m slightly different from the value of 1.275, for example, slightly higher.
  • Fig. 1 t shows an embodiment of a line terminating at one end in mid-series, and at the other end in mid-shunt.
  • the values of various elements as a function of the cut-off frequency ,fc are found as follows:
  • the left-hand termination shown in Fig. 14 is an example of a termination by. a mid-series cell the self-inductance L1 of which is equal to
  • the right-hand termination shown in Fig. 14 is an example of a termination in mid-shunt of a cell of proto-typefilter.
  • To the adjacent midseries termination a half cell of proto-type filter has been added in such a way that the self- 15 inductance of the termination is equal to and the shunt capacity of termination is equal to 29 Fig. 16 gives the values of Two for various values of m, 1- being the time of transmission, we the cut off pulsation.
  • auxiliary members such as the oscillator 1 associated with the modulator Z, and 545 whose frequency of 3.5 megacycles modulates the band A (0 200 kilocycles).
  • the two side-bands are filtered by the pass band filter 8 and by the mixing valve 9 passed onto the repeater l0 common to all the branches and thence on the cable or line I I.
  • a filter 12 may be associated with the retardation line 6 in order to eliminate frequencies greater than 3 megacycles, and which might fall within the range of frequencies of the band A modulated at 3.5 megacycles and which extends from 3.3 to 3.7 megacycles approximately.
  • Fig. 1'7 represents a simplified diagram of an embodiment of a receiver system suitable for receiving the divided band of frequencies.
  • a pass band filter l8 identical with the pass band filter 8 of the transmitting end which passes the two bands due to the modulation of the band A by the frequency of 3.5 megacycles.
  • a stage amplifier I! if neces sary permits a current of sufficient intensity to be applied to a double diode l8. After demodulation the current passes through a low-pass filter IS the cut-off frequency of which is higher 117.5
  • a band'elimination filter instead of the lowpass filter has the advantage of having for the same lower cut-off frequency a'lower phase distortion than that of the low-pass filter.
  • a retardation line 22 serves to equalise the periods of transmission in the two branches 'taking into consideration the retardation produced by the filters l6, l9 and 2
  • the valve 23 serves as an output valve, and is jointly connected with the valve 20 in the lower .branch transmitting the band A with a common output valve 24.
  • the original frequency band from 0 to 3 megacycles is thus reconstructed by the addition of the two bands A and B from the two circuit paths.
  • an auxiliary valve 25 may be inserted in one branch of the circuit in order to change the phase by 180".
  • An electric signal transmission system for the transmission of signals extending over a wide range of frequencies comprising two paths in parallel, the first of said paths including-a low pass filter to pass frequencies falling withinthe lower band, means for feeding a portion of the output from said filter to the second path equal in magnitudebut opposite in phase to the current-s of correspondingfrequencies-in said secondpath, means for modulating the other portion of the output from said filter by a higher frequency beyond the highest signal frequency and means for applying the outputs from the two paths to a transmission channel.
  • an auxiliary path between the output of the selecting means in the first path and the output of the second path, means in either the auxiliary path or the second path for producing a phase shift of 180 in the currents of the frequencies in the lower band in the one path with respect to the other, means in the first path for modulating the lower band of frequencies at a frequency higher than the highest signal frequency, and means for applying the outputs from the first and second paths to a transmission channel.
  • An electric signal transmission system for the transmission of signals extending over a wide range of frequencies, comprising two paths in parallel, the first of said paths including means for selecting the lower band of frequencies, the second path including means for passing the Whole range of frequencies and means for retarding the lower band of frequencies by the same amount as the said selecting means, an auxiliary path from'the output of said selecting means to the output of said second path, amplification means in said auxiliary path and amplification means in said second path adjusted so that the lower frequency band currents in the outputs of the auxiliary and second paths are equal and means in one of said paths for adjusting the phases of the currents therein in opposition to the currents in the other path, means in the first path for modulating the lower band of frequencies at a frequency higher than the highest signal frequency, and means for applying the outputs from the first and second paths to a transmission channel.
  • An electric signal transmission system for the transmission of signals extending over a wide frequency range, comprising two paths in parallel, the first of said paths including a low pass filter, means for modulating the band of frequencies passed .bysaid filter at a frequency higher than the highest signal frequency transmitted, and apass-band filter to the modulation products, the second of said paths passing all frequencies and including a retardation line for producing the same retardation as the low pass filter, an auxiliary path from the output of said low pass filter to the output of said second path and including means for producing a phase shift with respect to the currents in the said second path of 180 and for rendering the magnitude of the currents in the said auxiliary path equal to the magnitude of the currents in the second path, and means for applying the outputs from the first and second paths to a transmission channel.
  • the retardation line consists of a'series of cells of T formation, each cell comprising series inductances in the series arms, and a capacity in the shunt arm, the said series inductances being such that the mutual inductance therebetween forms a negative inductance in series with the condenser in the shunt arm.
  • the retardation line consists of a series of cells of T formation, each cell comprising series inductances in the series arms, and a negative inductance and capacity in the shunt arm, said negative inductance being formed by the mutual inductance between the two series inductances, which comprise a single coil wound on a core and provided with taps connected to the shunt condensers, the ratio of the diameter to the length of the winding between two successive taps being so chosen that the mutual inductance between two adjacent coil elements has a suitable value, the inductance of each section and the capacity of the shunt condensers being such that the iterative impedance of the line has the desired value, and the cut-off frequency is about 1.5 times the highest frequency to be transmitted.
  • the retardation line consists of a series of cells of T formation, each cell comprising series inductances in the series arms, and a negative inductance formed by the mutual inductance between adjacent ones of said series inductances, and a condenser in the shunt arm, the said series inductances comprising regularly spaced lumped windings on a common core.
  • the retardation line consists of a series of cells of T formation, each cell comprising series inductances in the series arms and a negative inductance formed by the mutual inductance between adjacent ones of said series inductances and a condenser in the shunt arm, said condenser being comprised by the capacity between at least part of the windings of said inductances and a metal electrode.

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  • Engineering & Computer Science (AREA)
  • Signal Processing (AREA)
  • Multimedia (AREA)
  • Computer Networks & Wireless Communication (AREA)
  • Coils Or Transformers For Communication (AREA)
  • Filters And Equalizers (AREA)
  • Details Of Television Systems (AREA)
  • Cable Transmission Systems, Equalization Of Radio And Reduction Of Echo (AREA)
US265476A 1938-04-23 1939-04-01 Transmission device Expired - Lifetime US2226728A (en)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
FR899956X 1938-04-23

Publications (1)

Publication Number Publication Date
US2226728A true US2226728A (en) 1940-12-31

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US265476A Expired - Lifetime US2226728A (en) 1938-04-23 1939-04-01 Transmission device

Country Status (5)

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US (1) US2226728A (enrdf_load_stackoverflow)
DE (1) DE899956C (enrdf_load_stackoverflow)
FR (1) FR845402A (enrdf_load_stackoverflow)
GB (1) GB527104A (enrdf_load_stackoverflow)
NL (1) NL63048C (enrdf_load_stackoverflow)

Cited By (14)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2416297A (en) * 1944-10-26 1947-02-25 Bell Telephone Labor Inc Wave transmission network
US2416683A (en) * 1944-10-26 1947-03-04 Bell Telephone Labor Inc Wave transmission network
US2510162A (en) * 1944-10-31 1950-06-06 Int Standard Electric Corp Aerial array
US2512945A (en) * 1946-06-28 1950-06-27 Heinz E Kallmann Radio-frequency transmission line section
US2525893A (en) * 1948-03-12 1950-10-17 Gloess Paul Francois Marie Telemetering system
US2564556A (en) * 1948-02-26 1951-08-14 Rca Corp Line delay in facsimile
US2598683A (en) * 1946-02-05 1952-06-03 Marcel J E Golay Corrected delay line
US2615978A (en) * 1947-10-14 1952-10-28 Motorola Inc Pulse width separation filter
US2656514A (en) * 1945-09-14 1953-10-20 Jr Joseph R Perkins Pulse producing system network
US2703389A (en) * 1953-11-17 1955-03-01 Hazeltine Research Inc Time-delay network
US2716733A (en) * 1950-05-10 1955-08-30 Exxon Research Engineering Co Variable bandwidth band-pass filter
US2719272A (en) * 1950-08-24 1955-09-27 Bell Telephone Labor Inc Reduction of transient effects in wide band transmission systems
US2907957A (en) * 1952-12-31 1959-10-06 Cgs Lab Inc Electrically variable delay line
US3046500A (en) * 1952-12-31 1962-07-24 Trak Electronics Company Inc Electrically variable delay line

Cited By (14)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2416683A (en) * 1944-10-26 1947-03-04 Bell Telephone Labor Inc Wave transmission network
US2416297A (en) * 1944-10-26 1947-02-25 Bell Telephone Labor Inc Wave transmission network
US2510162A (en) * 1944-10-31 1950-06-06 Int Standard Electric Corp Aerial array
US2656514A (en) * 1945-09-14 1953-10-20 Jr Joseph R Perkins Pulse producing system network
US2598683A (en) * 1946-02-05 1952-06-03 Marcel J E Golay Corrected delay line
US2512945A (en) * 1946-06-28 1950-06-27 Heinz E Kallmann Radio-frequency transmission line section
US2615978A (en) * 1947-10-14 1952-10-28 Motorola Inc Pulse width separation filter
US2564556A (en) * 1948-02-26 1951-08-14 Rca Corp Line delay in facsimile
US2525893A (en) * 1948-03-12 1950-10-17 Gloess Paul Francois Marie Telemetering system
US2716733A (en) * 1950-05-10 1955-08-30 Exxon Research Engineering Co Variable bandwidth band-pass filter
US2719272A (en) * 1950-08-24 1955-09-27 Bell Telephone Labor Inc Reduction of transient effects in wide band transmission systems
US2907957A (en) * 1952-12-31 1959-10-06 Cgs Lab Inc Electrically variable delay line
US3046500A (en) * 1952-12-31 1962-07-24 Trak Electronics Company Inc Electrically variable delay line
US2703389A (en) * 1953-11-17 1955-03-01 Hazeltine Research Inc Time-delay network

Also Published As

Publication number Publication date
FR845402A (fr) 1939-08-23
NL63048C (enrdf_load_stackoverflow)
GB527104A (en) 1940-10-02
DE899956C (de) 1953-12-17

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